Battery ignition system



May 16, 1967 G. SOHNER BATTERY IGNITION SYSTEM Filed July 27, 1964 3 Sheets-Sheet 1 y. 1967 G.SOHNER 3,319,618

/ BATTERY IGNITION SYSTEM- Filed July 2'1, 1964 a Sheets-Sheet 2 INVNIOP May 16, 1967 G. SOHNER BATTERY IGXITIONV SYSTEM Filed July 27; 1964 3 Sheets-Sheet 5 United States Patent 3,319,618 BATTERY IGNITION SYSTEM Gerhard Sr'ihner, Geradstetten, Kreis Waiblingen, Germany, assignor to Robert Bosch GmbH, Stuttgart, Germany Filed July 27, 1964, Ser. N 385,187

6 Claims. (Cl. 123-148) The present invention concerns a batttery ignition system for internal combustion engines. Systems of this kind conventionally comprise an ignition coil having a primary' and a secondary winding, a battery in circuit withsaid primary winding, and a transistor connected in said circuit with its emitter-collector circuit between one terminal of said battery and said primary winding. Moreover, an interrupter operated in synchronis'm with the engine is arranged in the base-collector circuit of the transistor and more specifically between the base of said transistor and the other terminal of said battery so that whenever the interrupter is. changed periodically between conductive and nonconductive positions, the transistor is also changed periodically between conductive and nonconductive conditions.

In conventiontal ignition systems of this type the transition of the transistor from conductive to nonconductive condition produces in the primary winding of the ignition coil a very high inductance voltage which makes it necessary to use a transistor which is not endangered by such high voltages applied tothe emitter-collector circuit. Such special transistors have been used but are comparatively very expensive.

It is therefore one object of the invention to provide for an arrangement of circuit components in a battery ignition system of such .a nature that even standard trausistors are capable to withstand elevated voltages applied to the emitter-collector circuit.

It is another object of the invention to provide for a system as set forth which requires only the addition of a small number of comparatively simple and inexpensive components to the conventional components of the system.

With above objects in view, the invention includes in a battery ignition system as set forth, the improvement consisting in electrical circuit means operatively connected with said transistor and producing, when said transistor is changed from conductive to non-conductive condition, a fiow of current from said base to said emitter of said transistor which flow is opposed to the normal current flow in said emitter-base circuit, whereby the change of the transistor from conductive to nonconductive condition is accelerated. Y

The novel features which are considered as characteristic for the invention are set forth inparticular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments. when read in connection with the accompanying drawings, in which;

FIG. 1 is a diagrammatic overall illustration of a battery ignition system;

the illustrated transistor-type battery ignition system is Patented May 16, 1967 adapted to be used in cooperation with a four-cylinder incore 36 of the ignition coil 11.

ternal combustion engine, not shown, and is supplied with energy by a storage battery 10. The arrangement comprises an ignition coil 11 which contains according to FIG. 2, a primary winding 12 and a secondary high voltage winding 13, both windings being connected to a common terminal 14 which is mounted in an insulating cover plate 15 of the ignition coil and is connected by a line 16 with electrical ground. The other end of the high voltage secondary winding 13 is connected by a cable 17 with the rotating contact arm 18 of a conventional distributor 20. The distributor shaft 23 is. also operatively connected with a 4-lobe cam 21 and driven by the engine, not shown. The cam 21 cooperates with an interrupter contact arm 22 which, in turn, cooperates witha stationary contact 35.

The insulated cover 24 of the distributor 20 contains four stationary electrodes which are consecutively engaged by the rotating contact arm 18 and which are connected via ignition cables 26 with the spark plugs 27, only one of the latter and of the cables 26 being shown in the drawing. a a

In order to control the current flowing through the primary winding 12 of the ignition coil and more particularly in order to periodically establish and discontinue such current flow in synchronism with the periodical change of the interrupter arm 22 between positions of engagement with and disengagement fi'om the contact 35, an arrangement 30 is provided as shown in FIGS. 1 and 2 which comprises a transistor 31 whose emitter is connected with the positive terminal of the battery 10 by the positive connection 32 and whose collector is connected with one end of the primary winding 12 of the ignition coil 11. The base of the transistor 31 is connected by a line 33 and a resistor 34 with the above mentioned stationary contact 35 of the interrupter so that the base of the transistor 31 will be connected with electrical ground i.e. with the negative terminal of the battery 10 every time the contact arm 32 engages the stationary contact 35. When this occurs, the transistor 31 is rendered conductive and is capable of carrying through its emitter-collector circuit a considerable current flowing through the'primary winding 12 whereby a strong magnetic field is produced in the iron However, as soon as the interrupter arm 22 is lifted by a cam 21 and thus dis engaged from the stationary contact 35, the transistor is changed from conductive to nonconductive condition whereby the current fiow through the primary winding 12 is interrupted with the result that hereby an igniting voltage impulse is produced inductively in the secondary high voltage winding 13 and applied via the distributor arm 18 to the respective one of the spark plugs 27.

In order to greatly shorten the time required by the transistor 31 for this transition from conductive to nonconductive condition and in order to reduce thereby the energy losses created during this transition period an inductance 39 equipped with an iron core 38 is connected in parallel with the emitter-base circuit of the transistor 31 However, this inductance forms together with a semiconductor rectifier 40 a series combination which is connected in parallel with the emitter-base circuit mentioned above. The rectifier 40 is so arranged that its direction of conductivity permits a current flow parallel with the normal current flow through the emitter-base circuit of the transistor 30. In addition, it is advisable to connect a series resistance as a current limiter 41 between the inductance 39 and the positive supply line 32, and to connect a capacitor 42- in parallel with the inductance 39.

As long as the interrupter arm 22 is in engagement with the stationary contact 35, not only the emitter-base current but also a parallel current I is capable of flowing over the engaged contacts 22, 35. The current 1,, produces in the iron core 38 of the inductance 39 a magnetic field. Therefore, as soon as the interrupter arm 22 is lifted or disengaged from the contact 35, the base current of the transistor 31 and also the current 1,, are interrupted. At the moment of this interruption the magnetic field still existing in the iron core 38 generates inductively a voltage across the winding 39by which the potential at the base of the transistor 31 is transitorily rendered positive relative to the potentialof the emitter. This gives rise to a blocking current which is opposite to :the normal direction of the base current of'the transistor so that the transition thereof to nonconductive condition is greatly accelerated.

It will be understood that the substantial advantage of the addition of at least the inductance 39 to the conventional circuit resides in the fact that the transistor 31 is capable of withstanding unusually high blocking voltages appearing between emitter and collector because the inductance 39 produces a transitory positive voltage peak at the moment of the interruption of the current flow caused by the disengagement of the interrupter contacts.

Referring now to FIGS. 3 and 4 illustrating a second embodiment of the invention, it can be seen that the overall arrangement according to FIG 3 is quite similar to that of FIG. 1 with the only exception that two wires connect two terminals at the bottom of the ignition coil 11 with the arrangement 30. In FIGS3 and 4 all those elements which are identical with those of FIGS 1 and 2 are desig? nated by the same numerals.

It does not appear to be necessary to describe those portions of FIGS. 3 and 4 which are identical with those of the arrangement according to FIGS. 1 and 2. However, it can-be seen that instead of the series combination 39, 40, 41 of FIG. 2, the embodiment according to FIGS. 3 and 4 comprises a third winding 48 mounted in the ignition coil 11 on the same core 36 as the primary and secondary windings 12 and 13, and a series combination of a rectifier 50 and a resistor 49 connected in series with the third winding 48, the entire combination of winding 48, resistor .49 and rectifier 50 being connected in parallel with the emitter-base circuit of the transistor 31 between the lines 32 and 33.

The production of the igniting voltage impulses by periodically alternating engagement and disengagement of the interrupter members 22 and 35 is exactly the same as described above. .I-Io'weven'in order to shorten considerably the period of time which the transistor 31 requires for the'transition from its conductive to its nonconductive condition and in order to reduce the energy loss occurring during this transition period in the transistor, the above described auxiliary circuit including the elements 48, 49 and 50 is provided. his to be noted that also in this case the rectifier 50 is so arranged that it permits, when the interrupter contacts 22, 35 are in engagement, a flow of current from line 32 through winding 48 and the series combination 49, 50 and from there transistor 31 in a direction opposite to the normal currentfiow therethrough. This means that simultaneously with the production of the ignition voltage impulse, the blocking voltage induced in the third winding 48 causes the above mentioned flow of current and'applies to the base B of the transistor 31 a. potential which is positive relative to that of the emitter. The result of this is that the transistor 31 is very rapidly changed from conductive to non-conductive condition. An additional advantage obtained by this arrangement is that breakdown voltage of the emitter-collector circuit is greatly increased.

Referring now to the further embodiment of the invention according to FIG. 5, it can be seen that this is a modification of the arrangement according to FIG. 4, the most important difference between the two embodiments being the addition of a second transistor and accordingly of another additional winding to the ignition coil. In the illustrated example of the invention, those elements which are identical with the first described embodiments have the same reference numerals. Two transistors 51 and 52 are provided, the emitter-collector circuits thereof are connected in series with each other and in circuit with the primary winding 12. The ignition coil comprises in addition to the secondary winding 13 two additional windings 53 and 54 mounted on the common iron core 36. The winding 53 is associated with the transistor 51 and is arranged in a circuit connected in parallel with the emitter-base circuit thereof and containing also a resistor 55 and a rectifier 56 as a series combination. The rectifier 56 is so arranged that current from the winding 53 can flow therethrough and further toward the interrupter contacts 35 and 22 in the same direction as the normal current flow through the emitter-base circuit of transistor 51. The second additional winding 54 has one of its ends connected with a junction point between the collector of transmitter 51' and the emitter of transistor 52, while its opposite end is connected in circuit with a. series combination comprising another rectifier 57 and a resistor 58 to the base of the transistor 52. The transistors 51 and 52 are controlled jointly in a manner similar to that described above by the interrupter 22, 35. Therefore, the base of transistor 51 is connected with contact 35 via a protective resistor 60 and the base of transistor 52 is similarly connected via another protectiveresistor 61, the two 'bases being decoupled from each other by an additional rectifier 62 as illustrated. The rectifier 57 is also arranged with its direction of conductivity in such a manner that current flowing from winding 54 through this rectifier will flow toward contact 34 in parallel with the normal current flow through the emitter-base circuit of transistor 52.

.As long as the interrupter arm 22 is in engagement with the stationary contact 35, the two transistors 51 and 52 are in conductive condition because the bases thereof are connected to electrical ground or negative potential and a sufiicient base current can flow through the resistors 60 and 61. However, this base current is interrupted as soon as the contact arm 22 is lifted by the cam 21 from the stationary contact 35. Due to the interruption of the base current, both transistors 51 and 52 change from conductive to nonconductive condition and consequently interrupt the current that was flowing through the primaryv winding 12 of the ignition coil 11. Hereby an igniting voltage impulse for the spark plugs 27 is produced in the secondary winding 13. However, simultaneously a'similar voltage impulse is induced inthe two additional windings 53 and 54 whereby the potential at each of the bases of the transistors 51 and 52 is rendered positive relative to the existing potential at the emitters thereof whereby the transition from conductive to nonconductive condition of the transistors is accelerated.

It will be understood that the arrangement according'to FIG. 5 has a still greater etficiency than the arrangement according to FIG. 4 on account of the greater number of transistors. In order to make sure that the voltage induced in the primary winding 12 upon the interruption of the primary current is evenly distributed between the.

two transistors, it is advisable to provide for the additional resistors 65 and 66 connected in parallel with the emitter-collector circuits of the transistors as illustrated. These two resistors 65 and 66 should be of equal size.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of a battery ignition system including at least one transistor diflering from the types described above.

While the invention has been illustrated and described as embodied in a battery ignition system including at least one transistor and means for accelerating the transi tion from conductive to nonconductive condition of the transistor or transistors, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a battery ignition system for internal combustion engines including an ignition coil having a primary and a secondary winding, a battery connected to said primary winding, a transistor, having its emitter-collector path between one terminal of said battery and said primary winding, and an interrupter connected between the base of said transistor and other terminal of said battery and changing between conductive andnonconductive positions for periodically changing said transistor between conductive and nonconductive conditions including, in combination, inductance means and rectifier means connected with each other as a series-combination, said seriescombinatiori being connected in parallel with the emitter-collector path of said transistor, said rectifier means being arranged in said series-combination in such a manner that the direction of its conductivity permits, when the interrupter is in conductive position, a current to flow through said SCYiESrCOHlbiHZfiOIl in parallel with the emitter-base current through said transistor, and permits, when said interrupteris in nonconductive position, a current to flow through, said series-combination and against the normal current direction through said emitter-base path of said transistor, whereby the change of said transistor from conductive condition to nonconductive condition is accelerated,

2. In a battery ignition system for internal combustion engines including an ignition coil having a primary and a secondary winding, a battery connected to said primary winding, a transistor having its emitter-collector path between one terminal of said battery and said primary winding, and an interrupter connected between the base of said transistor and the other terminal of said battery and changing between conductive and nonconductive positions for periodically changing said transistor between conduc-- tive and nonconductive conditions including, in combination, inductance means and rectifier means connected with each other as a series-combination, said series-combination being connected in parallel with the emitter-collector path of said transistor, capacitor means connected in parallel with said inductance means, said rectifier means being arranged in said series-combination in such a manner that the direction of its conductivity permits, when the interrupter is in conductive position, a current to flow through said series-combination in parallel with the emitter-base current through said transistor, and permits, when said interrupter is in nonconductive position, a current to flow through said series-combination and against the normal current direction through said emitter-base path of said transistor, whereby the change of said transistor from conductive condition to nonconductive condition is accelerated.

3. In a battery ignition system for internal combustion engines including an ignition coil having a primary and a secondary winding, a battery connected to said primary winding, a transistor having its emitter-collector path between one terminal of said battery and said pri 6 mary winding, and an interrupter connected between th base of said transistor and the other terminal of said battery and changing between conductive and nonconductive positions for periodically changing said transistor between conductive and nonconductive conditions including, in combination, inductance means, limiting resistance means and rectifier means connected with each other as a series-combination, said series-combination being connected in parallel with the emitter-collector path of said transistor, said rectifier means being arranged in said series-combination in such a manner that the direction of its conductivity permits, when the interrupter is in conductive position, a current to flow through said seriescombination in parallel with the emitter-base current through said transistor, and permits, when said interrupter is in nonconductive position, a current to flow through said series-combination and against the normal current direction through said emitter-base path of said transistor, whereby the change of said transistor from conductive condition to nonconductive condition is accelerated 4. In a battery ignition system for internal combustion engines including an ignition coil having a primary and a secondary winding, a battery connected to said primary winding, a transistor having its emitter-collector path between one terminal of said battery and said primary winding, and an interrupter connected between the base of said transistor and the other terminal of said battery and changing between conductive and nonconductive positions for periodically changing said transistorbetween conductive and nonconductive conditions including, in combination, inductance means, limiting resistance means and rectifier means connected witheach other as a series-combination, said series-combination being connected in parallel with the emitter-collector path of said transistor, capacitor means connected in parallel with said inductance means, said rectifier means being ar ranged in said series-combination in such a manner that the direction of its conductivity permits, when the interrupter is in conductive position, a current to flow through said series-combination in'parallel, with the emitter-base current through said transistor, and permits, when said interrupter is in non-conductive position, a current to flow through said series-combination and against the normal current direction through said emitter-base path of said transistor, whereby the change of said transistor from conductive condition to nonconductive condition is accelerated.

5. In a battery ignition system for internal combustion engines including an ignition coil having a primary and a secondary winding, a battery connected to said primary winding, a transistor having its emitter-collector path be tween one terminal of said battery and said primary winding, and an interrupter connected between the base of said transistor and the other terminal of said battery and changing between conductive and nonconductive positions for periodically changing said transistor between conductive and nonconductive conditions including, in combination, at least one additional winding in said ignition coil and magnetically coupled with said primary winding thereof, resistance means and rectifier means connected in series with said additional winding so as to form a series-combination, said series-combination being connected in parallel .with the emitter-base path of said transistor, said rectifier means being so arranged that its direction of conductivity permits a current to ilow therethrough in parallel with the normal how of base current of said transistor when the latter is in conductive condition, and permitting, when said transistor is rendered nonconductive, a current to fiow from said additional winding oppositeto the normal current flow from emitter tobase of said transistor, whereby the change of said transistor from conductive to nonconductive condition is accelerated.

6. In a battery ignition system for internal combustion engines including an ignition coil having a primary and thereof, diiferent resistance means and rectifier means connected in series with each of said additional windings, respectively so as to form correspondingly different seriescombinations, each of said series-combinations being connected in parallel with the emitter-base path of the repermitting, when the respectively associated transistor is spectively associated transistor, said rectifier means being so arranged that its direction of conductivity permits a current to flow therethrough in parallel with the normal fiow of base current of the respectively associated transistor when the latter is in conductive condition, and

rendered nonconductive, a current to flow from the respectively associated additional winding opposite to the normal current flow from emitter to base of the respectively associated transistor, whereby the change of said transistors from conductive to nonconductive condition is accelerated.

References Cited by the Examiner UNITED STATES PATENTS 3,016,476 1/1962 Bat'aille 315209 3,046,447 7/ 1962 Kirk et a1 123148 3,178,608 4/1965 McKendry l23148 3,184,638 5/1965 Wood 123148 3,213,320 10/ 1965 Worrell 123- 148 3,218,512 11/1965 Quinn 123148 3,259,798 7/1966 Yonge 315-209 MARK NEWMAN, Primary Examiner. LAURENCE M. GOODRIDGE, Examiner. 

1. IN A BATTERY IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES INCLUDING AN IGNITION COIL HAVING A PRIMARY AND A SECONDARY WINDING, A BATTERY CONNECTED TO SAID PRIMARY WINDING, A TRANSISTOR, HAVING ITS EMITTER-COLLECTOR PATH BETWEEN ONE TERMINAL OF SAID BATTERY AND SAID PRIMARY WINDING, AND AN INTERRUPTER CONNECTED BETWEEN THE BASE OF SAID TRANSISTOR AND OTHER TERMINAL OF SAID BATTERY AND CHANGING BETWEEN CONDUCTIVE AND NONCONDUCTIVE POSITIONS FOR PERIODICALLY CHANGING SAID TRANSISTOR BETWEEN CONDUCTIVE AND NONCONDUCTIVE CONDITIONS INCLUDING, IN COMBINATION, INDUCTANCE MEANS AND RECTIFIER MEANS CONNECTED WITH EACH OTHER AS A SERIES-COMBINATION, SAID SERIES-COMBINATION BEING CONNECTED IN PARALLEL WITH THE EMITTER-COLLECTOR PATH OF SAID TRANSISTOR, SAID RECTIFIER MEANS BEING ARRANGED IN SAID SERIES-COMBINATION IN SUCH A MANNER THAT THE DIRECTION OF ITS CONDUCTIVITY PERMITS, WHEN THE INTERRUPTER IS IN CONDUCTIVE POSITION, A CURRENT TO FLOW THROUGH SAID SERIES-COMBINATION IN PARALLEL WITH THE EMITTER-BASE CURRENT THROUGH SAID TRANSISTOR, AND PERMITS, WHEN SAID INTERRUPTER IS IN NONCONDUCTIVE POSITION, A CURRENT TO FLOW THROUGH SAID SERIES-COMBINATION AND AGAINST THE NORMAL CURRENT DIRECTION THROUGH SAID EMITTER-BASE PATH OF SAID TRANSISTOR, WHEREBY THE CHANGE OF SAID TRANSISTOR FROM CONDUCTIVE CONDITION TO NONCONDUCTIVE CONDITION IS ACCELERATED. 